Safety plug and outlet

ABSTRACT

Disclosed herein is a safety plug and outlet which may be readily interchanged for a standard electrical outlet and which has a unique safety arrangement whereby it is practically impossible for a person employing the device of this invention to get an electrical shock when inserting the plug of an appliance or other equipment into the outlet. The device contemplates the use of a depressor in the plug which operates a switch in the positive line to the outlet so that no current flows to the positive contact blades of the outlet until the plug is practically completely inserted in the socket. By this arrangement, it is practically impossible for one to touch a prong of the plug which could be partially inserted in the socket and thus receive an electrical shock. The switch in the positive line may operate through the use of a snap-acting spring so that the connection in the switch is positively and securely made or else is biased open so that the switch will not flicker between an off and on position. The invention further contemplates an adapter which may be inserted into the standard junction box of an ordinary wall outlet so that the device of the present invention may be used without any significant structural changes in any area where its use may be desired.

United States Patent Primary Examiner-David Smith, Jr A!lorney-Shermanand Shalloway ABSTRACT: Disclosed herein is a safety plug and outletwhich may be readily interchanged for a standard electrical outlet andwhich has a unique safety arrangement whereby it is practicallyimpossible for a person employing the device of this invention to get anelectrical shock when inserting the plug of an appliance or otherequipment into the outlet. The device contemplates the use of adepressor in the plug which operates a switch in the positive line tothe outlet so that no current flows to the positive contact blades ofthe outlet until the plug is practically completely inserted in thesocket. By this arrangement, it is practically impossible for one totouch a prong of the plug which could be partially inserted in thesocket and thus receive an electrical shock. The switch in the positiveline may operate through the use of a snap-acting spring so that theconnection in the switch is positively and securely made or else isbiased open so that the switch will not flicker between an off and onposition. The invention further contemplates an adapter which may beinserted into the standard junction box of an ordinary wall outlet sothat the device of the present invention may be used without anysignificant structural changes in any area where its use may be desired.

PATENTEU JUL27 l9?! SHEET 1 OF 2 a 0 T N m mm m W W Y R N E H ATTORNEYSSAFETY PLUG AND OUTLET This invention relates to electrical connectorsand particularly to electrical connectors including a socket and plugwith safety provisions for preventing the user thereof from getting anelectrical shock when the plug is inserted into the socket.

Electrical connectors in the form of plug and sockets having safetyfeatures represent a highly developed art. However, there is acontinuing effort on the part of industry and individuals to produce asafety plug of greater efficiency and one which is more economical toproduce. The present invention is a product of such continuing effortand represents an improvement over prior art devices in its simplicityof design and ease of manufacture.

The device of the present invention assures that its user cannot receivean electrical shock while connecting the plug of an appliance to anelectrical outlet and is particularly advantageous in applications wherechildren are present and by their curious nature likely to attemptto usethe plug. In these applications, children may often insert the plug inthe socket only partially and thus leave an exposed prong of the plugwhich is connected to a live power source and thereafter con tact such alive prong with some type of a cylindrical or slender instrument such asa screwdriver, toy or any other device which is susceptible to insertionin a narrow opening. If such a device is electrically conductive, thechild could receive a severe shock, resulting in sometimes fatal injury.

With this situation in mind, l have devised a safety plug and outletwhich avoids the possibility of a live prong of an electrical plug beingexposed and which device may be readily interchanged into a standardhome outlet or may be supplied as original structure in a home or otherbuilding where children are likely to attempt use of such devices.

The advantages of my safety plug and outlet over prior art devices arenumerous. The device may be readily interchanged with standard walloutlets and adapters for standard plugs can be easily provided. Thedevice is easily constructed and can be manufactured in great quantitiesat significant cost savings over other safety connectors. Constructionof the device does not require any highly specialized or complicatedcomponents and most of the components of the device are available in thepresent market. The switch member in the positive power source of thesocket is preferably controlled by a snap-acting spring so that there isno chance of sparking or shorting and the power supplied through theplug will not flicker or cut on and off in response to any jarring orother vibration that might be imposed upon the plug.

From this brief description of some of its advantages, it will berecognized that the invention has as its primary object the provision ofa simple and efficient safety plug and socket.

Another object of this invention is to provide a safety plug and outletthat can be readily interchanged for a standard plug and outlet with aminimum amount of time and effort.

Still a further object of this invention is to provide a safety plug andoutlet including a depressor element carried by the plug which operatesa switch in the positive line power source to control the power passedto the positive contact blades.

Yet a further object of this invention is to provide a safety plug andoutlet as above described wherein the switching mechanism includes asnap-acting spring so that the current is switched either full on orfull off.

Still a further object of this invention is to provide a safety plug andoutlet wherein no power will be supplied to the prongs of the plug untilthe plug is in the outlet to the extent that the prong is protected bythe face of the plug.

These and other objects of the invention will become apparent to thoseof ordinary skill in the related art, when consideration is given to thefollowing detailed description of a preferred embodiment, which is setforth as exemplary only, which description is given in conjunction withthe accompanying drawings wherein:

FIG. 1 illustrates an exploded perspective of a device manufacturedaccording to the present invention;

FIG. 2 illustrates in perspective the switch carried in the positivepower line by the adapter oft present invention;

FIG. 3 illustrates partially in cross section an assembled devicemanufactured according to the present invention;

FIG. 4 is a cross section taken along line 44 of FIG. 3 and illustratesan assembled device constructed according to the present invention;

FIG. 5 is an exploded perspective ofa standard plug and the false bottomadapter which may be provided in connection with the present invention;and

FIG. 6 illustrates in cross section a modified mounting arrangement inconnection for the adapter and socket of the invention.

Referring now to FIG. 1, the plug 1, socket 2 and adapter 3 are shown inexploded relationship. The plug 1 may be a stan-.

dard appliance plug connected through the cord 4 to any electricalappliance (not shown). The plug includes prongs 5 and has been modifiedwith respect to a standard plug to include a depressor 6 which isprovided for a purpose which will become apparent hereinafter.

The socket 2 is substantially a standard unit and includes the prongopenings 7 and dog ears 8 having slots 9 through which screws 10 passfor connecting the socket to the adapter. The socket 2 is normallyconstructed of a plastic material which is nonconductive to electricityand a standard socket is modified to the extent that in the center ofeach plug face between the prong openings 7 is provided depressoropening 11.

The depressor openings extend completely through the socket and providea channel for carrying the pegs 12 which are positioned in the channelsfor slidable movement axially of the opening.

The adapter 3 includes the contact blades for the prongs of the plug 1which extend into hollowed portions of the socket 2. Switches 13 arerecessed in pockets 14 of the adapter and are connected between thepositive power source and the positive contact blades 15.

The positive contact blades I5 and the negative contact blades 16 areseparated from the switch 13 by an insulator 17. The connection betweenthe positive blades 15 and the contact 18 (FIG. 2) of the switch 13 isillustrated schematically by the line 19.

A stop 20 is provided on the adapter to position the switch arm 21 ofthe switch when the switch is in its open position as illustrated inFIG. 3. The adapter also includes channels 22 which are provided toreceive the screws 10 for connecting the socket to the adapter. Tabs 23having openings 24 are also provided on the extremity of the adapter forconnecting the adapter to a standard junction box.

The insulator 17 has a hole 25 through which passes the peg 12 fordepressing the switch arm 21. As is apparent, the depressor 6 and peg 12could be a continuous unit passing through the depressor opening 11 andthe hole 25 to depress the switch on 21. However, the arrangementillustrated in FIG. I is preferable since the use of a recesseddepressor prevents the depressor from becoming bent or broken throughuse.

Referring to FIG. 3, the switch preferred for use in the presentinvention is illustrated. The sw tch includes a switch arm 21 which hasan over center, snap-acting spring 30 integral therewith. The switch armis connected to a bracket 31 as shown in FIG. 2 by a rivet or likestructure 32 and the bracket includes a lip 33 beneath which the spring30 is caught. Contact 18 on member 34 is provided for passing currentwhen the connection is made with contact 35 on the underside of theswitch arm 21. The member 34 is connected to the positive contact blades15 through the line 19 illustrated schematically in FIG. I so that whenthe peg 12 depresses on the point 36 of the switch arm, the contact 35is sprung into engagement with the contact 18 and the power input isthus connected to the positive contact blades.

By providing a snap-type spring 30 in the switch 13, when a slightamount of pressure is applied to the point 36, the connection betweencontacts 35 and 18 is assured through the bias of the spring. When thepeg is removed so that no pressure is applied to the point 36, thespring 30 operates in the opposite or up direction so that the switcharm 21 is biased into contact with the stop 20. By this arrangement theconnection between contacts 35 and 18 will not flutter or flip from offto on and so forth since the slight amount of pressure applied by thepeg 36 is amplified through the spring and switch arm to ensure theconnection between the contacts.

Referring now to FIGS. 3 and 4, the device of the present invention inassembled relation is illustrated. A wall junction box 40 is shownmounted on a wall joist 41, by screws, nails, etc., 42. In substitutingthe device of the present invention for a standard wall socket, thepositive line source is connected at point 43 which is secured in theconductor 44 for passing current to the switch 13. There is a separateswitch for each of the two outlets. The body structure of the adapter 3is of insulation material to keep the socket from shorting out.

The negative line is connected to the negative contact blades 16 as at45. Once the positive and negative lines have been connected to theadapter, the adapter may be mounted in the junction box by screws 46passing through the tabs 23 and connected to the flange 47. As can beseen from FIGS. 3 and 4, the contact 18 of the member 34 is connected asat 50 to the positive contact blades 15.

Once the adapter 3 is mounted in the junction box 40, the socket 2having the peg 12 within the channel 51, is connected to the adapter.The socket may be connected through the dog ears 8 with a screw passingthrough the slot 9 and threaded into the internally threaded channel 22.When the socket 2 is mounted on the adapter 3, the insulator 17 ispositioned between the contact blades and the switch 13 to assure thatthe contact blades are insulated from the power source connected to theswitch. A plate 53 may then be mounted over the socket by a screw 54 andthe device is ready for insertion of the plug 1. If the plug 1 isprovided with a depressor 6, the depressor will force the peg l2 axiallydownward and cause same to apply pressure on the point 36 and makeconnection between the contacts 35 and 18. The snap-acting spring 30will amplify the pressure applied to the peg l2 and bias the contact 35against the contact 18. As the plug 1 is removed, the depressor nolonger applies force to the peg l2 and the force of the spring 30 willoperate in the up direction to open the switch and break the powersupply to the positive contact blades 15. The dimensions of the peg anddepressor can of course be regulated so that the depressor will operatethe switch by force on the peg only when the plug is substantially flushwith the face of the socket. The upward movement of the switch arm 21 islimited by the stop which is insulated to prevent the device fromshorting out.

If a standard plug is to be employed with the device of the presentinvention, an adapter in the form of a false bottom as is illustrated inFIG. 5 is necessary. The false bottom includes a plate 60 having slots61 and a depressor 6. The false bottom or plate is slid over the prongsS of the plug 1, with the prongs passing through the slots 61 so that astandard plug is easily adapted for use with the device of thisinvention.

An alternative arrangement for the mounting of the device of the presentinvention is illustrated in FIG. 6. In this arrangement, the tab 23 isoffset upwardly from the adapter so that it may be connected to theflange 47 along with the dog ear 8 of the socket. Since the flange of astandard junction box is usually provided at the mouth of the box asopposed to recessed within the box as illustrated in FIG. 3, aconversion unit will preferably have the mounting structure illustratedin FIG. 6.

As it is apparent, the device described as a preferred embodiment isexemplary only and various modifications will become apparent to thoseskilled in the art. For example, the switch 13 could be any of astandard variety including a pivoted lever depressing a contact memberin response to pressure of the peg 12 on the lever. The units 2 and 3may also be of a one-piece construction. Further, the invention isreadily adaptable for use in conjunction with three-pronged plugs,

it being merely necessary to realign the components of the 5 adapter inorder to receive the peg and depressor provided on the plug.

The present invention can be adjusted to provide any degree of safetythat is desired and the plate 53 may be constructed such that it wouldbe practically impossible for any object to be inserted between the plugand the socket while the switch 13 is actuated to supply power to thepositive contact blades. Further, a child would not receive a shockmerely by inserting a conductive instrument within the opening leadingto the positive contact blades since no power is supplied to the contactblades until the peg 12 has been depressed to actuate the switch. Inorder to receive a shock from the safety plug of this device, one wouldhave to insert some type of an instrument in the depressor openings 11and while holding the depressor in a compressed position, at the sametime insert some type of an instrument into the positive contact bladeopenings. When the plug of the device is used to connect an electricalappliance, the dimensions of the depressor 6 and peg 12 are such thatthe plug must be substantially flush with the face of the socket beforeany power is supplied to the positive contact blades from which onecould receive a shock by touching the positive prong 5. However, whenthe depressor is sufficiently inserted into the socket to depress theswitch and cause power to pass to the positive contact blades, the plugis so close to the face of the socket that it is substantiallyimpossible, without extreme effort and agility, to contact the prongssince the body of the plug fits over the face of the socket and may berecessed therein if desired.

The preferred embodiment of the invention has been described in detailand several modifications have been discussed. However, it is to beunderstood that the preferred embodiment is exemplary only and is notintended to limit the range of equivalents that are within the scope ofthe invention as defined by the terms of the appended claims. Further,the alternatives and modifications of the device of the invention asdiscussed herein previously are by no means exhaustive of themodifications that will become apparent to those of ordinary skill inthe art and which will be equivalent of the express terms of theappended claims.

What I claim is:

l. A safety electrical outlet device for use with a plug having firstand second spaced electrically conductive prongs and a depressor prongcentrally disposed between said first and second prongs, said deviceincluding a socket having first and second prong receiving openingsspaced therein to receive said first and second prongs of said plug anda third depressor receiving opening centrally disposed between saidfirst and second openings to receive said depressor prong of said plugwhen said first and second prongs of said plug are inserted in saidfirst and second openings; and

an adapter attached to said socket, said adapter including first contactblades aligned with said first opening in said socket to receive saidfirst prong of said plug, second contact blades aligned with said secondopening in said socket to receive said second prong of said plug, anelongated, nonconducting peg having a first end slidable in said thirdopening in said socket and a second end, a first terminal connected withsaid first contact blades and adapted to be connected with a source ofelectricity, a second terminal adapted to be connected with said sourceof electricity, and snap-acting switch means aligned with said thirdopening in said socket and selectively connecting said second terminalwith said second contact blades, said snap-acting switch means includinga stationary contact connected with said second contact blades, a switcharm connected with said second terminal and carrying a movable contact,and a spring blade affixed to said switch arm and having a normalposition and an operative position, said movable contact being placed inelectrical contact with said stationary contact when said spring bladeis in said operative position, said movable contact being spaced fromsaid stationary contact when said spring blade is in said normalposition, and said second end of 5 said peg operatively engaging saidsnap-acting switch means such that said peg is forced against saidsnap-act ing switch means to place said spring blade in said operativeposition when said depressor prong of said plug is inserted completelyin said third opening in said socket whereby electricity from saidsource is supplied to said depressor prong at a central position betweensaid first and second slots.

1. A safety electrical outlet device for use with a plug having firstand second spaced electrically conductive prongs and a depressor prongcentrally disposed between said first and second prongs, said deviceincluding a socket having first and second prong receiving openingsspaced therein to receive said first and second prongs of said plug anda third depressor receiving opening centrally disposed between saidfirst and second openings to receive said depressor prong of said plugwhen said first and second prongs of said plug are inserted in saidfirst and second openings; and an adapter attached to said socket, saidadapter including first contact blades aligned with said first openingin said socket to receive said first prong of said plug, second contactblades aligned with said second opening in said socket to receive saidsecond prong of said plug, an elongated, nonconducting peg having afirst end slidable in said third opening in said socket and a secondend, a first terminal connected with said first contact blades andadapted to be connected with a source of electricity, a second terminaladapted to be connected with said source of electricity, and snap-actingswitch means aligned with said third opening in said socket andselectively connecting said second terminal with said second contactblades, said snap-acting switch means including a stationary contactconnected with said second contact blades, a switch arm connected withsaid second terminal and carrying a movable contact, and a spring bladeaffixed to said switch arm and having a normal position and an operativeposition, said movable contact being placed in electrical contact withsaid stationary contact when said spring blade is in said operativeposition, said movable contact being spaced from said stationary contactwhen said spring blade is in said normal position, and said second endof said peg operatively engaging said snap-acting switch means such thatsaid peg is forced against said snap-acting switch means to place saidspring blade in said operative position when said depressor prong ofsaid plug is inserted completely in said third opening in said socketwhereby electricity from said source is supplied to said second contactblades.
 2. The device as recited in claim 1 wherein said second end ofsaid peg engages said switch arm to force said switch blade to saidoperative position.
 3. The device as recited in claim 1 wherein saidplug includes a prong adapter having first and second spaced slotstherein to receive first and second prongs and carrying said depressorprong at a central position between said first and second slots.